Acoustic horn



Oct. 25,1927. w, R, REsPEss ACOUSTIC HORN Original Filed Dec. a. 1923 2 Sheets-Sheet IIMIIMI INVENTQR. W\L.L.IAM. R. KEsPEzss.

ATTORNEY}.

1,646,707 w. RESPESS I ACOUSTIC HORN v Original Filed Dec. a, 1923 2 Sheets-Sheet 2 BY 19a. 1 r ATTO EY.

Patented a. 25, 1927.

7 UNITED. sing mnn'rs, 17o ennnns LABORATORIES,

IPORATIO N OF NEW JERSEY.

PAT N E -pf XZVIIQLIAMFR. Business. or s'r. Geese-E, "nnw rem, A s mes iunsnn Assiei n'io, on NEWARK, NEW JEItsEY, A con- AooiisrIo-Honn angina application filed' December 8, remain rid. 67?),42'50. Divided and nus aeatan-nea September so, 1924.

My inventionrelates broadly to soundam plifyinghorn, and more particularly to a construction of acoustic horn for electromagnetic sound reproducers. This a plica'tion is a division of my application S.N; 679,480, filed "December 8; 1923', 'wherein I have claimedthe method of making the acoustic horn the construction which is claimed in the present application. r One of the objects ofmy invention is to provide atconstruction of sound amplifying horn which may be. inexpensively manufactured on a quantity production basis.

Another object of my invention is to provide" a"horn.for use with electromagnetic sound reproducers which has improved acoustic properties.

Still another objectof my invention is to provide a construct-ionof acoustic horn, in which the horn is" pressed from flat material \vhieh is securely bonded together at adjacent edges: during the manufacture and treated" to obtain-a substantially invisible seam withacousti c' properties of good'qual- Other and further objects ofmy invention will. be understood from the specification hereinafter following by reference to the accompanying drawings, in which Figure 1 represel ts one portion of material "used in forming the horn, ofvvhich it will be understood [there aretwoportions one right and'one le ftfblanked. out in one of its possible shapes"; FigIQis a perspective view' of one form of blank material which I may use in the construction of the horn; Fig.3 isa cross sectional view showing the cellular Wall construction of Fig. 2;

Fig. 4 represents the portion ofthe horn illustrated in Fig. 1, being hot pressed in a die-forming mold; Fig. 5 represents a side elevation partially in cross section of the die-forming mold shown in Fig. l with the portion of the horn illustratedin 1 betion of the shaping block; Fig. represents the portion of the horn shown in F g. 1

after it hasbeen pressed by the shaping .moldjFig. S is a plan view of oneofthe V-shaped members which I may employ to fill in the gap formed during theprocess of pressing the portionof the horn illustrated ing shaped therein; Fig. dis a side eleva Serial no. 740,757.

inFig. 1;}Figg9' illustrates in plan View one of "the gluing molds used in the process of forming the complete horn from the two portions which have been completed in the pressing moldshowing the sectionaIiZed gluing cores in position; Fig. 10 represents the other portion of the gluing mold which is used in conjunction with thefportion' of the gluing moldillustrated in Fig.9; 11' and 12 are end views of the gluing cores i1--' lustrated in position in Fig.9; Fig. 13is a cross sectional view taken through the glitmg mold showing the sections of the horn in positionduring the process of gluing; Figs. 14, 15 and 16 represent different methods of securing the joints of 'the parts of the horn in forming the seam; and Fig. 17 is a plan View looking beneath the throat of the horn fro illustrating the position of the V-sha p'ed provide a pair of split dies and an inflatable 1 core form which maybe'expanded to shape apl'astic material in the dies Which is sub"- sequent'ly dried forming the hoi'n-.. S'ueh horns are expensive in maniacal-resend it is difficult to secure uniformity of produc-"-.

tion, resulting in a quantity of rejections. Such horns require considerable polishing with inherentexpense in labor.

In'my invention I provide a' construction of horn in Which'the material of the-horn when completed is substantially in its original compact solid state whereby the tone quality is a function of the original {ma/re rial used. By reason of the pressing operations the horn may be manufactured less expensivel-y than in the case of building up laminated papier mac-he horns or molding horns from plastic material. By reason of the impregnating treatment to Which Iin'ay subject my construction, I preserve the inherent tone qiiality' of the original material.

'lheappearance o'fmy ho'rn when completed is not unlike the appearance of the papier mechhorn or molded horn, although, by

reason of its processofnianufacture itis ings reference character 1 represents one lessexpensive than any prior construction of horn.

Referring more particularly to the draw form of a flat sheet of material which has been cut by means of a band saw or die pressed from a flat leather board or other suitable material. The grain of the material may run at a substantial angle with its lon itudinal axis for purposes which will beIaterapparent. Inshaping these pieces of material a' number may be cut to provide lefts and others out to provide rights, it being merelynecessaryto reverse the glazed surface of the material with reference to the I bandsa-w or die press. v

. The material may be. laminated in three plies as represented in Figs. 2 and 3, the Outer plies 2' and 3 being less, in thickness than the. inner perforated core sheet 1. The useof the perforated sheet 4 interposed between the outer walls 2 and 3 provides a cellular or hollow wall construction which i modifies theacoustie properties of the horn.

The material shown in Fig. 1may be dipped in. a pitch; rosin compound, making it mechanically strong and preserving the inherenttone quality ofthematerial through the reduction inthe possibility. of vibration.

Afterthe dipping processthe horn portion be immediately pressed, but if it becomes hard before the pressing process it maybe steamed to return it to a softened condition..

.Q When n' softened condition the horn portioncutfto shape as in Fig. 1 is hot-pressed in a forming mold. as shown in Fig. 4. Th mes. right and left forming mold of the contour represented by reference character the inside being machine finished to .presenta smooth wall to the horn mate- I rial when' it is. pressed therein byaformgze re 6-.. h edge of he ing i 5 are approximately one-half inchabove the .center line of the die and is supported in a position to permit approizimately a one fourth. inch wall space between the shaping moldfi and the inner wall of the die-form ing mold .5 to allow for the material of the -horn represented at 1. This operation removesa quantity of the moisture from the horn portion and rapidly dries the material.

It will beunderstood that the shaping molds are steam packed or otherwise heated.

.,. .After the conclusion of the pressing op .eration the horn portion lfwill have the shape representedin Fig. 7, wherein the slotted portion 7- shown in Fig. 1 is spread tothe V shape represented by reference character 8,- I provide a; V-shaped throat portion of horn material 9 shown in Fig. 8

V which is inserted in'the gap and forced and locked therein with suitable cement or glue flush with the surface of the horn. Each of the horn portions at-the conclusion Offthe .ance. or the horn comprisin hot pressing operation is dry and hard and hasan excess of material along its edges.

'This, excess material .is cut off by a tool formingthe edges in any one of the several manners shown in Figs. 14, 15 and 16. If I utilize a blank Wlt-l'lOllfitlle slot '7 therein and of slightly differingshape, I may form. one-half of the horn completely without in clus'ionof a V-shaped throat portion, the

particles of the material at the throat being stressed and compressed.

The portions of the horn thus formed are then ready for the gluing process and are removed to the gluin molds of which there is a r ght and left, the left being shown in Fig. 9 by reference character 10, and the right at 15 in-Fig. 10. The gluing molds each align on a center line which is not the case as in the forming molds, as previously described. Guide pins 11, 12 and 14 are formed on the face of the gluing mold in,

such manner they are aligned and fitted into cooperating holes 11*, 12 and l lflon the gluing mold section 15.which is ithe right hand section. In the gluing process onehalf portion of the horn is placed in the gluing mold with glue or cement between adjacent edges and then the core .members 16 and 17 placed therein. The horn may now be again pressed and the joint tightly U able .cradles19 and 19. j The core sections are madelin two parts as represented, by

reference characters 16 and 17 in Figs/11 and12, with joint means QO-and 21 therebetween, whereby the core members maybe independently removed afterrthe gluing process has been completed. The gluing process involves pressing process which maybe accomplished in amultiple division bailingv press. s

InFig. '14 the joints of the horn section are halved together as represented by reference character 16. In Fig. 15 the jointisa beveled joint slanted inthe direction.represented by reference character 17 orthe slant .maybein the opposite .direction as repre sented by referencecharacter 18 in Fig. 16.-

.fIn Fig. .17 I-have illustrated the appar- 7 1 V d two sections, 1 and 1 with the V shaped throat members -9 and 9 When I press. the completehalves of the horn each separately, these match' togetherfwithonly a longitudinal seam at'the front and rear without the inter-positionof the throat members. Any seams which-may 'beleftafter completion ofthegluing and with an edging tool.

. tions in the surface.

pressing process are removed by a flexible shaft sander tool which may be moved with in the horn to smooth the seam or outside thereof. The periphery of the bell may be squared and leveled by placing it upon a sander belt. The edge may then be rounded The end of the horn may be squared upon a sander wheel or belt and a ferrule secured thereon. The horn may then be againdipped to render it moistureproof and then a suitable filler applied to the seam or upon any imperfec- A' final coating of crystalline varnish may be applied to the horn to add to its appearance.

By my improved process in the manufac-' ture of acoustic horns, I provide amethod by which the horn material may be blanked out simultaneously in numbers of fifty or more. The material may be softened either by impregnating in the pitch rosin coma pound or in hot or cold water, or by steaming. The shaping process for both left and right portions of the horn is quickly performed while the flat material is in softened condition. The parts are hot pressed.

The horn may be dipped to secure a pleasing appearance and a suitable surface appearance imparted thereto. By reason of the impregnation previously referred to and the cellular construction of the wall of the horn, pleasing acoustic properties are se cured. It will be appreciated that my process greatly increases the possibilities of horn production over construction of horns as heretofore known. The locked joint formed by either the halved together edges or overlapping beveled edges insures the formation of a shell substantially opaque to sound.

lVhile I have described my invention in certain particular embodiments, it is to be understood that various modifications may be'made', and that I intend no limitations upon the invention other than are imposed 2. An acoustic horn comprising in com! bination a pair of substantially semi-circular shaped side members having abutting edges for forming a horn, each'flof said side members being cut away at the throat thereof, and an auxiliary member shaped to close said cut away portion, said side members being bound together at abutting edges for conveying sound.

WILLIAM R. RnsPEss.

.whereby said horn providesan acoustic shell 

